Normally when you create controllers, helpers and models inside an engine,
they are treated as if they were created inside the application itself.
This means that all helpers and
named routes from the application
will be available to your engine’s controllers as well.

However, sometimes you want to isolate your engine from the application,
especially if your engine has its own router. To do that, you simply need
to callisolate_namespace.
This method requires you to pass a module where all your controllers, helpers and models should be nested
to: